Which of the following gases might a cryogenic intermodal tank transport?

The correct choice is the transportation of argon and helium in a cryogenic intermodal tank. Cryogenic intermodal tanks are specifically designed to transport gases that are stored at extremely low temperatures, typically below -150 degrees Celsius. Argon and helium are both noble gases that remain in a gaseous state at standard temperatures and can be liquefied and transported in such specialized tanks.

Hydrogen, while it can be transported in cryogenic conditions, is often handled in a different manner due to its flammability and other hazards associated with it. Methane, though it can also be transported cryogenically (as liquefied natural gas), typically requires tanks designed for pressurized or cryogenic transport but not necessarily intermodal tanks that focus solely on cryogenic applications. Ammonia, while it is a common hazardous material, is not transported in cryogenic tanks as it has a different storage requirement and is usually handled under pressure or at ambient temperatures.

Therefore, argon and helium are the most suitable gases that fit the criteria of being transported in cryogenic intermodal tanks, making this answer the correct choice.